Coverage-dependent adsorption of nitrous oxide (N2O) on perfect and defective Cu(0 0 1) surfaces: A DFT investigation with and without van der Walls forces

•N2O adsorptions on the flat and defective Cu(001) surfaces were examined.•DFT-PBE and DFT-vdW-DF calculations have been performed.•On the flat surface, the vdW-DF adsorption energies are better than those of PBE.•Increase of adsorption energy was noted on the defective surface, using the PBE.•vdW-DF scheme exhibited instability for N2O adsorption on the defective surface.